Applications for LTCC technology have been expanding as flat board technology has been augmented with three-dimensional features including cavities, channels, solid tubes, formed shapes, sacrificial volume materials (SVM) and various embedded components such as resistors, capacitors, inductors and heat sinks. See generally U.S. Pat. Nos. 7,494,557 and 7,155,812, both of which are incorporated herein by reference in their entirety.
Recently, techniques have been developed for fabricating continuous EMI full tape thickness features (FTTF). These are based on via fill technology and use the full thickness of the tape to improve performance. In the case of conductors, this is accomplished by substituting full thickness lines for surface-printed traces that are typically much thinner. FIG. 1 shows the increased cross-sectional thickness provided by FTTF as compared to a surface printed trace (designated as a thick film line feature in FIG. 1). FIG. 2 provides a perspective view of a tape having features similar to the middle tape in the stack of FIG. 1. As indicated in FIG. 1, the increased cross-sectional area results in correspondingly reduced resistivity. The result is paths with very low resistance. FTTF technology has also been used to produce fences for EMI structures that are superior to traditional via fences because of their ability to block more line-of-sight radiation.
It is desirable to provide for improvements in the use of FTTF technology in EMI structures.